Matlab GUI to select and plot data from csv file.

Hello community,

I am trying to write a code for a matlab GUI that let the user browser and select a .csv data file, then reads and shows the data, then select variables for x-axis and y-axis and finally plots the selected data.

the code runs well till I click plot botton it shows the error below.

Can anyone help please.

The code

function csvPlotterGUI
    % Create the main figure
    mainFig = figure('Name', 'CSV Plotter', 'NumberTitle', 'off', 'Position', [100, 100, 800, 400], 'ResizeFcn', @resizeCallback);

    % Create UI components
    fileButton = uicontrol('Style', 'pushbutton', 'String', 'Select CSV File', 'Callback', @selectFileCallback);
    fileText = uicontrol('Style', 'text', 'String', 'Selected File:');
    fileDisplay = uicontrol('Style', 'text');

    xText = uicontrol('Style', 'text', 'String', 'Select X Variable:');
    xPopup = uicontrol('Style', 'popupmenu');

    yText = uicontrol('Style', 'text', 'String', 'Select Y Variable:');
    yPopup = uicontrol('Style', 'popupmenu');

    plotButton = uicontrol('Style', 'pushbutton', 'String', 'Plot', 'Callback', @plotCallback);

    % Data display table
    dataTable = uitable('ColumnName', {}, 'ColumnWidth', {175});

    % Variables to store data
    selectedFile = '';
    data = table();

    % Set initial positions
    setPositions();

    % Callback functions
    function setPositions()
        figPosition = get(mainFig, 'Position');
        buttonWidth = 120;
        buttonHeight = 30;
        textWidth = 200;
        textHeight = 20;

        % Update positions based on the figure size
        set(fileButton, 'Position', [20, figPosition(4) - 50, buttonWidth, buttonHeight]);
        set(fileText, 'Position', [150, figPosition(4) - 45, textWidth, textHeight]);
        set(fileDisplay, 'Position', [350, figPosition(4) - 45, textWidth, textHeight]);

        set(xText, 'Position', [20, figPosition(4) - 100, textWidth, textHeight]);
        set(xPopup, 'Position', [150, figPosition(4) - 100, buttonWidth, buttonHeight]);

        set(yText, 'Position', [20, figPosition(4) - 150, textWidth, textHeight]);
        set(yPopup, 'Position', [150, figPosition(4) - 150, buttonWidth, buttonHeight]);

        set(plotButton, 'Position', [20, figPosition(4) - 200, buttonWidth, buttonHeight]);

        set(dataTable, 'Position', [500, 50, figPosition(3) - 520, figPosition(4) - 100]);
    end

    function resizeCallback(~, ~)
        setPositions();
    end

    function selectFileCallback(~, ~)
        [filename, path] = uigetfile('*.csv', 'Select CSV File');
        if filename ~= 0
            selectedFile = fullfile(path, filename);
            set(fileDisplay, 'String', selectedFile);
            data = readtable(selectedFile);
            variables = data.Properties.VariableNames;
            set(xPopup, 'String', variables);
            set(yPopup, 'String', variables);
            updateDataTable();
        end
    end

    function updateDataTable()
        if isempty(data)
            return;
        end

        % Display data in the uitable
        set(dataTable, 'Data', table2cell(data), 'ColumnName', data.Properties.VariableNames);
    end

    function plotCallback(~, ~)
        if isempty(selectedFile) || strcmp(selectedFile, 'Selected File:')
            errordlg('Please select a CSV file first.', 'Error');
            return;
        end

        xVarIndex = get(xPopup, 'Value');
        yVarIndex = get(yPopup, 'Value');

        xData = data.(data.Properties.VariableNames{xVarIndex});
        yData = data.(data.Properties.VariableNames{yVarIndex});

        figure;
        plot(xData, yData, 'o-');
        xlabel(data.Properties.VariableNames{xVarIndex});
        ylabel(data.Properties.VariableNames{yVarIndex});
        title('CSV Data Plot');
    end
end

The error

Unrecognized function or variable 'mainFig'.

Error in untitled/setPositions (line 30)

figPosition = get(mainFig, 'Position');

Error in untitled/resizeCallback (line 53)

setPositions();

Error using untitled

Error while evaluating Figure SizeChangedFcn.

You might see this error if any of the variables in the figure's SizeChangedFcn are undefined when the figure becomes visible. Consider waiting to set the figure's Visible property to 'on' until all the SizeChangedFcn variables are defined.

Warning: 'popupmenu' control requires a non-empty Character vector

Control will not be rendered until all of its parameter values are valid

Warning: 'popupmenu' control requires a non-empty Character vector

Control will not be rendered until all of its parameter values are valid

Warning: Column headers from the file were modified to make them valid MATLAB identifiers

before creating variable names for the table. The original column headers are saved in the

VariableDescriptions property.

Set 'VariableNamingRule' to 'preserve' to use the original column headers as table variable

names.

Error using plot

Invalid data argument.

Error in untitled/plotCallback (line 91)

plot(xData, yData, 'o-');

Error while evaluating UIControl Callback.

Answer 1

[Anjaneyulu Bairi]

Hi,

I understand that you are trying write a code for a matlab GUI app which has the option to the user to select a .csv data file, then reads and shows the data, then select variables for x-axis and y-axis and finally plots the selected data.You can try the below troubleshooting steps to resolve the errors.

• The error "Unrecognized function or variable 'mainFig'." says 'mainFig' is unrecognized. The object 'mainFig' is getting created after the function call 'resizeCallback', which is calling 'setPositions' and this function has reference to the 'mainFig' object which is not created yet.
• To resolve that error create the 'mainFig' without the function callback like below.

 mainFig = figure('Name', 'CSV Plotter', 'NumberTitle', 'off', 'Position', [100, 100, 800, 400]);

• Now set the callback property to 'mainFig' using set function like below and it will remove all the errors in the code.

set(mainFig,"ResizeFcn",@resizeCallback);

Here is the complete code for reference.

function csvPlotterGUI
    % Create the main figure
    mainFig = figure('Name', 'CSV Plotter', 'NumberTitle', 'off', 'Position', [100, 100, 800, 400]); % create the main figure object without function call
    set(mainFig,"ResizeFcn",@resizeCallback); % now add function call
    % Create UI components
    fileButton = uicontrol('Style', 'pushbutton', 'String', 'Select CSV File', 'Callback', @selectFileCallback);
    fileText = uicontrol('Style', 'text', 'String', 'Selected File:');
    fileDisplay = uicontrol('Style', 'text');

    xText = uicontrol('Style', 'text', 'String', 'Select X Variable:');
    xPopup = uicontrol('Style', 'popupmenu');

    yText = uicontrol('Style', 'text', 'String', 'Select Y Variable:');
    yPopup = uicontrol('Style', 'popupmenu');

    plotButton = uicontrol('Style', 'pushbutton', 'String', 'Plot', 'Callback', @plotCallback);

    % Data display table
    dataTable = uitable('ColumnName', {}, 'ColumnWidth', {175});

    % Variables to store data
    selectedFile = '';
    data = table();

    % Set initial positions
    setPositions();

    % Callback functions
    function setPositions()
        figPosition = get(mainFig, 'Position');
        buttonWidth = 120;
        buttonHeight = 30;
        textWidth = 200;
        textHeight = 20;

        % Update positions based on the figure size
        set(fileButton, 'Position', [20, figPosition(4) - 50, buttonWidth, buttonHeight]);
        set(fileText, 'Position', [150, figPosition(4) - 45, textWidth, textHeight]);
        set(fileDisplay, 'Position', [350, figPosition(4) - 45, textWidth, textHeight]);

        set(xText, 'Position', [20, figPosition(4) - 100, textWidth, textHeight]);
        set(xPopup, 'Position', [150, figPosition(4) - 100, buttonWidth, buttonHeight]);

        set(yText, 'Position', [20, figPosition(4) - 150, textWidth, textHeight]);
        set(yPopup, 'Position', [150, figPosition(4) - 150, buttonWidth, buttonHeight]);

        set(plotButton, 'Position', [20, figPosition(4) - 200, buttonWidth, buttonHeight]);

        set(dataTable, 'Position', [500, 50, figPosition(3) - 520, figPosition(4) - 100]);
    end

    function resizeCallback(~, ~)
        setPositions();
    end

    function selectFileCallback(~, ~)
        [filename, path] = uigetfile('*.csv', 'Select CSV File');
        if filename ~= 0
            selectedFile = fullfile(path, filename);
            set(fileDisplay, 'String', selectedFile);
            data = readtable(selectedFile);
            variables = data.Properties.VariableNames;
            set(xPopup, 'String', variables);
            set(yPopup, 'String', variables);
            updateDataTable();
        end
    end

    function updateDataTable()
        if isempty(data)
            return;
        end

        % Display data in the uitable
        set(dataTable, 'Data', table2cell(data), 'ColumnName', data.Properties.VariableNames);
    end

    function plotCallback(~, ~)
        if isempty(selectedFile) || strcmp(selectedFile, 'Selected File:')
            errordlg('Please select a CSV file first.', 'Error');
            return;
        end

        xVarIndex = get(xPopup, 'Value');
        yVarIndex = get(yPopup, 'Value');

        xData = data.(data.Properties.VariableNames{xVarIndex});
        yData = data.(data.Properties.VariableNames{yVarIndex});

        figure;
        plot(xData, yData, 'o-');
        xlabel(data.Properties.VariableNames{xVarIndex});
        ylabel(data.Properties.VariableNames{yVarIndex});
        title('CSV Data Plot');
    end
end

I hope it helps to resolve your query.

[Zakaria]

Thank you for the feedback. By the time you posted yiu answer I have solved the problem.

Thank you again for you help.

function csvPlotterGUI
    % Create the main figure
    mainFig = figure('Name', 'CSV Plotter', 'NumberTitle', 'off', 'Position', [100, 100, 800, 400], 'ResizeFcn', @resizeCallback);

    % Create UI components
    fileButton = uicontrol('Style', 'pushbutton', 'String', 'Select CSV File', 'Callback', @selectFileCallback);
    fileText = uicontrol('Style', 'text', 'String', 'Selected File:');
    fileDisplay = uicontrol('Style', 'text');

    xText = uicontrol('Style', 'text', 'String', 'Select X Variable:');
    xPopup = uicontrol('Style', 'popupmenu');

    yText = uicontrol('Style', 'text', 'String', 'Select Y Variable:');
    yPopup = uicontrol('Style', 'popupmenu');

    plotButton = uicontrol('Style', 'pushbutton', 'String', 'Plot', 'Callback', @plotCallback);

    % Data display table
    dataTable = uitable('ColumnName', {}, 'ColumnWidth', {175});

    % Variables to store data
    selectedFile = '';
    data = table();

    % Set initial positions
    setPositions();

    % Callback functions
    function setPositions()
        figPosition = get(mainFig, 'Position');
        buttonWidth = 120;
        buttonHeight = 30;
        textWidth = 200;
        textHeight = 20;

        % Update positions based on the figure size
        set(fileButton, 'Position', [20, figPosition(4) - 50, buttonWidth, buttonHeight]);
        set(fileText, 'Position', [150, figPosition(4) - 45, textWidth, textHeight]);
        set(fileDisplay, 'Position', [350, figPosition(4) - 45, textWidth, textHeight]);

        set(xText, 'Position', [20, figPosition(4) - 100, textWidth, textHeight]);
        set(xPopup, 'Position', [150, figPosition(4) - 100, buttonWidth, buttonHeight]);

        set(yText, 'Position', [20, figPosition(4) - 150, textWidth, textHeight]);
        set(yPopup, 'Position', [150, figPosition(4) - 150, buttonWidth, buttonHeight]);

        set(plotButton, 'Position', [20, figPosition(4) - 200, buttonWidth, buttonHeight]);

        set(dataTable, 'Position', [500, 50, figPosition(3) - 520, figPosition(4) - 100]);
    end

    function resizeCallback(~, ~)
        setPositions();
    end

    function selectFileCallback(~, ~)
        [filename, path] = uigetfile('*.csv', 'Select CSV File');
        if filename ~= 0
            selectedFile = fullfile(path, filename);
            set(fileDisplay, 'String', selectedFile);
            data = readtable(selectedFile);
            variables = data.Properties.VariableNames;
            set(xPopup, 'String', variables);
            set(yPopup, 'String', variables);
            updateDataTable();
        end
    end

    function updateDataTable()
        if isempty(data)
            return;
        end

        % Display data in the uitable
        set(dataTable, 'Data', table2cell(data), 'ColumnName', data.Properties.VariableNames);
    end

    function plotCallback(~, ~)
        if isempty(selectedFile) || strcmp(selectedFile, 'Selected File:')
            errordlg('Please select a CSV file first.', 'Error');
            return;
        end

        xVarIndex = get(xPopup, 'Value');
        yVarIndex = get(yPopup, 'Value');

        xData = data.(data.Properties.VariableNames{xVarIndex});
        yData = data.(data.Properties.VariableNames{yVarIndex});

        figure;
        plot(xData, yData, 'o-');
        xlabel(data.Properties.VariableNames{xVarIndex});
        ylabel(data.Properties.VariableNames{yVarIndex});
        title('CSV Data Plot');
    end
end

Answer 2

[Image Analyst]

Use the current figure, gcf:

figPosition = get(gcf, 'Position');

Also see MAGIC - MATLAB Generic Imaging Component

that has all the wiring for selecting a folder and listing files in a listbox that the user can click on and display the plot.

OK you can just pass in mainFig to the functions that need it, like:

% Set initial positions in main program by calling the nested function setPositions().
setPositions(mainFig);

% Callback functions
function setPositions(mainFig)
figPosition = get(mainFig, 'Position');

Answer 3

[Voss]

Notice what the error message tells you: "You might see this error if any of the variables in the figure's SizeChangedFcn are undefined when the figure becomes visible. Consider waiting to set the figure's Visible property to 'on' until all the SizeChangedFcn variables are defined."

Following that advice, i.e., making the figure invisible when it's created and making it visible only after mainFig and all the other variables are defined, e.g.:

function csvPlotterGUI

% Create the main figure

mainFig = figure( ...

'Name', 'CSV Plotter', ...

'NumberTitle', 'off', ...

'Position', [100, 100, 800, 400], ...

'ResizeFcn', @resizeCallback, ...

'Visible','off');

% ... your code to create UI components here ...

set(mainFig,'Visible','on');

% Callback functions

% ... the rest of your code here ...

end

should resolve the error.

Note that you do not need to explicitly call setPositions() when initializing because that is (effectively) your figure's ResizeFcn, so it gets called when the figure is made visible.

Complete code for reference:

function csvPlotterGUI
    % Create the main figure
    mainFig = figure('Name', 'CSV Plotter', 'NumberTitle', 'off', 'Position', [100, 100, 800, 400],'ResizeFcn', @resizeCallback,'Visible','off');
    
    % Create UI components
    fileButton = uicontrol('Style', 'pushbutton', 'String', 'Select CSV File', 'Callback', @selectFileCallback);
    fileText = uicontrol('Style', 'text', 'String', 'Selected File:');
    fileDisplay = uicontrol('Style', 'text');

    xText = uicontrol('Style', 'text', 'String', 'Select X Variable:');
    xPopup = uicontrol('Style', 'popupmenu');

    yText = uicontrol('Style', 'text', 'String', 'Select Y Variable:');
    yPopup = uicontrol('Style', 'popupmenu');

    plotButton = uicontrol('Style', 'pushbutton', 'String', 'Plot', 'Callback', @plotCallback);

    % Data display table
    dataTable = uitable('ColumnName', {}, 'ColumnWidth', {175});
    
    % Variables to store data
    selectedFile = '';
    data = table();
    
    set(mainFig,'Visible','on')
    
    
    % Callback functions
    function setPositions()
        figPosition = get(mainFig, 'Position');
        buttonWidth = 120;
        buttonHeight = 30;
        textWidth = 200;
        textHeight = 20;

        % Update positions based on the figure size
        set(fileButton, 'Position', [20, figPosition(4) - 50, buttonWidth, buttonHeight]);
        set(fileText, 'Position', [150, figPosition(4) - 45, textWidth, textHeight]);
        set(fileDisplay, 'Position', [350, figPosition(4) - 45, textWidth, textHeight]);

        set(xText, 'Position', [20, figPosition(4) - 100, textWidth, textHeight]);
        set(xPopup, 'Position', [150, figPosition(4) - 100, buttonWidth, buttonHeight]);

        set(yText, 'Position', [20, figPosition(4) - 150, textWidth, textHeight]);
        set(yPopup, 'Position', [150, figPosition(4) - 150, buttonWidth, buttonHeight]);

        set(plotButton, 'Position', [20, figPosition(4) - 200, buttonWidth, buttonHeight]);

        set(dataTable, 'Position', [500, 50, figPosition(3) - 520, figPosition(4) - 100]);
    end

    function resizeCallback(~, ~)
        setPositions();
    end

    function selectFileCallback(~, ~)
        [filename, path] = uigetfile('*.csv', 'Select CSV File');
        if filename ~= 0
            selectedFile = fullfile(path, filename);
            set(fileDisplay, 'String', selectedFile);
            data = readtable(selectedFile);
            variables = data.Properties.VariableNames;
            set(xPopup, 'String', variables);
            set(yPopup, 'String', variables);
            updateDataTable();
        end
    end

    function updateDataTable()
        if isempty(data)
            return;
        end

        % Display data in the uitable
        set(dataTable, 'Data', table2cell(data), 'ColumnName', data.Properties.VariableNames);
    end

    function plotCallback(~, ~)
        if isempty(selectedFile) || strcmp(selectedFile, 'Selected File:')
            errordlg('Please select a CSV file first.', 'Error');
            return;
        end

        xVarIndex = get(xPopup, 'Value');
        yVarIndex = get(yPopup, 'Value');

        xData = data.(data.Properties.VariableNames{xVarIndex});
        yData = data.(data.Properties.VariableNames{yVarIndex});

        figure;
        plot(xData, yData, 'o-');
        xlabel(data.Properties.VariableNames{xVarIndex});
        ylabel(data.Properties.VariableNames{yVarIndex});
        title('CSV Data Plot');
    end
end